Systems and methods for waking wireless LAN devices

ABSTRACT

A system and method for wireless waking computing devices over a computer network is provided. A signal is broadcast over the network that includes one or more device specific wake-up data sequences. Each device specific wake-up data sequence includes multiple iterations of the hardware address of the wireless network card associated with that device. While in a reduced power or “sleep mode”, the wireless network card monitors wireless channels for packets containing a wake-up data sequence. If a wake-up data sequence is received, the sequence is matched against the hardware address information for that network card. If a match is determined, the network card sends a signal to the computing device causing full system power to be restored. A signal is sent to the network confirming that the device has been successfully woken from the sleep mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/995,188, titled “Systems and Methods for Wake-on-LAN for Wireless LANDevices,” filed on Nov. 24, 2004, and issued on Jul. 8, 2008 as U.S.Pat. No. 7,398,408, which is incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to systems and methods for accessingcomputing devices over wireless local area networks and moreparticularly to systems and methods for waking computing devices from apowered down or sleep state with signals sent over wireless local areanetworks.

BACKGROUND OF THE INVENTION

As computer usage in the workplace becomes ever more pervasive,efficient network administration becomes an increasingly complex task.In an office environment, individual computer terminals are typicallynetworked to a server over a local area network (LAN) such as anEthernet LAN. In a LAN, each computer communicates with the networkthrough a LAN controller. Typically, the LAN controller is housed on anetwork interface card (NIC), sometimes called a LAN card or Ethernetcard. However, recently, the LAN controllers are being integrateddirectly into computer motherboards. Each LAN controller is representedas a node on the LAN by a unique identification number. A servercomputer also connected to the LAN acts as the gateway to outsidenetworks and as centralized data storage. From the administrator's end,LAN implementations allow administrative tasks such as softwareinstallation, virus scanning, file management, network email service,data backups, etc., to be performed over the network from a singlecentral location. Through use of access levels, the networkadministrator may manage all the other computers or nodes on the networkfrom his or her computer. From the user end, LAN implementations allowaccess to the Internet, shared file storage space and access to sharednetworked output devices, such as printers.

Due in part to the dynamic technology dependent nature of today'sworkplace, network administrators must constantly perform functionsrequiring access of individual network nodes from the administrator'scomputer. These functions can include configuring new nodes, updatingand installing software, adding network printers, scanning for viruses,and file back-ups, to name a few. Typically, many of theseadministrative functions are scheduled for execution after normalbusiness hours so as to minimize interference with user applicationsduring the work day. However, during these after hour times, individualcomputers on the LAN may be in one of a variety of power conservingmodes, also known as sleep modes. Typically, the power conserving modescause the display to be put in a low power state, the hard drive to bespun down and even the microprocessor to reduce its clock frequency orto be shut down completely. Having the computers powered down can makeit difficult if not impossible to schedule and implement after hoursnetwork events. If the administrator has to physically turn on eachmachine, at least some of the efficiencies of centralized networkadministration are lost.

This problem of needing to wake-up computers over the LAN led to theinvention of a protocol known as MAGIC PACKET technology. MAGIC PACKETtechnology is a proprietary hardware solution incorporated into the cardor board-based Ethernet controller for waking up a PC over the LANdeveloped and owned by Advanced Micro Devices, Inc. of Sunnyvale, Calif.Before entering a powered down or sleep mode, the LAN controller is putinto a MAGIC PACKET mode. In this mode, the device will no longergenerate any network transmits, but will monitor all incoming frames todetermine if any of them is a MAGIC PACKET frame. The LAN controllerwill scan all incoming frames addressed to the node for a specific datasequence, which indicates to the controller that this is a MAGIC PACKETframe. A MAGIC PACKET frame must meet the general requirements for thespecific LAN technology employed, such as SOURCE ADDRESS, DESTINATIONADDRESS and CRC. Also in the frame is the MAGIC PACKET, which is aspecific sequence consisting of 16 duplications of the IP address of thespecific node. The sequence can be located anywhere within the packet,but must be preceded by a synchronization stream. The synchronizationstream allows the scanning state machine to be much simpler byidentifying the location of the sequence.

If the address matching circuit determines that the MAGIC PACKET forthat node has arrived, the MAGIC PACKET mode is disabled and full poweris restored to the system allowing the network administrator to performdata backups, software installations, etc. Alternatively, full power maybe restored by conventional means such as depressing a key on thekeyboard or moving/clicking the mouse. After the desired operation hasbeen performed, or after a sufficient time period has expired, a commandsignal may be sent the node over the LAN to return the node to the powersaving MAGIC PACKET MODE. Because the LAN controller already hasbuilt-in address matching circuitry in order to recognize regular framesaddressed to the node, implementation of MAGIC PACKET technology issimplified. For a full description of MAGIC PACKET technology refer toU.S. Pat. No. 6,049,885 hereby incorporated by reference in itsentirety.

Due in part to advances in liquid crystal displays and batterytechnology as well as reductions in disk drive and circuit board size,demand for laptop, palmtop and other wireless computer devices has grownsignificantly. The typical LAN is no longer comprised only of desktopcomputers physically tethered to the network. Instead, today's officeenvironment consists of a mixture of wired and wireless computer deviceswhich often have their own internal wireless cards. Also, in order toavoid the expense of retrofitting office space with networkcommunication cables, wireless network cards are even being used withstationary desktop-type computers. As a result, the need arose to extendthe functionality of LAN access to wireless devices. To accommodate thisneed, a standard for wireless LAN, known as IEEE 802.11x was created.Using one or more wireless access points (APs), distributed throughoutan office space, wireless devices are able to seamlessly connect to theLAN in a manner identical to and at speeds comparable to tetheredworkstations over short distances. Each wireless device has a wirelessnetwork interface card with a transceiver that facilitates two waycommunication with the AP. The AP has a service set identifier (SSID)which is a 32 character identifier attached to the header of packetssent over the wireless LAN (WLAN). The SSID differentiates one WLAN fromanother. All access points and all devices attempting to connect to aspecific WLAN must use the same SSID. Each node on the WLAN has a uniquehardware destination address that uniquely identifies that node.

The presence of wireless device nodes on the LAN complicates theimplementation of wake-up over the LAN. Firstly, wireless devices arenot always plugged into a permanent power source. Usually, these devicesare capable of running off line power or their own internal batteries.Secondly, wireless devices access the LAN by communicating with aspecific access point. Thus, in order for the network administrator tosend a message to a particular node, he must know the SSID of the accesspoint that the wireless device communicates with. However, because ofthe portable nature of wireless devices, the administrator may not knowthe location of the each device within the premises, and thus, theaccess point with which each device will communicate. As a result, itbecomes difficult to address a wake-up signal to specific devicesknowing only the destination address of each device.

The description herein of various advantages and disadvantagesassociated with known apparatus, methods, and materials is not intendedto limit the scope of the invention to their exclusion. Indeed, variousembodiments of the invention may include one or more of the knownapparatus, methods, and materials without suffering from theirdisadvantages.

SUMMARY OF THE INVENTION

Therefore, it would be desirable to provide a system for wirelesslywaking computer devices out of reduced power or sleep mode over awireless local area network. It would also be desirable to provide anetwork card for use with wireless devices that is capable of entering awireless signal monitoring state and of monitoring received wirelesssignals while in the state for a wake up data sequence.

The present invention mitigates or solves the above-identifiedlimitations in known solutions, as well as other unspecifieddeficiencies in known solutions. A number of advantages associated withthe present invention are readily evident to those skilled in the art,including economy of design and resources, transparent operation, costsavings, etc.

Disclosed herein are various exemplary mechanisms for achievingwake-over-wireless LAN. Also disclosed herein are various exemplarymechanisms for scanning a plurality of wireless channels in a wirelessLAN with a wireless device to find a wake-up data sequence for thatdevice, and then, waking the wireless device from a powered down modewhen the wake up data sequence that device is received. Also disclosedherein is a power management scheme for use with a mini-PCI bus-basedwireless network interface card for receiving wireless wake-on LANsignals.

In accordance with one embodiment of the present invention, a method forputting a wireless device into a reduced power mode such that the devicecan be wirelessly returned to a full power mode and for returning thedevice to a full power mode using signals transmitted over a wirelessLAN is provided. The method comprises the steps of putting a device intoa reduced power mode, activating a receiver to scan a plurality ofwireless data channels for a MAGIC PACKET, scanning each channel for apredetermined time period, and if a MAGIC PACKET for that device isreceived, returning that device to a full power mode, otherwise,deactivating the receiver for another predetermined time period.

In accordance with an additional embodiment of the present invention, awireless network controller is provided. The wireless network controllercomprises a wireless transceiver operable to scan a plurality of datachannels; power control circuitry for selectively supplying andwithdrawing power to and from the transceiver, timing circuitry forcontrolling the period of time that power is supplied to and withdrawnfrom the transceiver, a comparator for comparing a data sequencereceived by the transceiver with a sequence stored in memory, and acontroller for sending a wake-up signal when the received signal matchesthe sequence stored in memory.

In accordance with yet another embodiment of the present invention, anetwork interface card is provided. The network interface card comprisesa connector for communicatively connecting the card to a wireless deviceand for supplying power to the card, a wireless transceiver for scanninga plurality of data channels, a power control circuit which is activatedwhen the card receives a signal that the device has entered a powersaving mode, a timing control circuit for controlling the time thatpower is supplied to and withdrawn from the transceiver, a comparatorfor comparing a data sequence received by the transceiver with asequence stored in memory, and a controller for sending a wake-up signalin response to the output of the comparator.

In accordance with an additional embodiment of the present invention, awireless device operable to go into a powered down mode and to be wokenfrom the powered down mode when a wake-up data sequence for that deviceis received over a wireless LAN is provided. The wireless devicecomprises a power saving sleep mode operable to reduce or eliminatepower to all components of the wireless device except a wireless networkcontroller. The wireless device also comprises a wireless transceiverfor monitoring a plurality of wireless channels for an incoming wake-updata sequence signal. The wireless device further comprises a comparatorfor comparing an incoming wake-up data sequence signals with a signalstored in memory and a controller for restoring power to the wirelessdevice if the incoming wake-up data sequence matches a signal stored inmemory.

Still further features and advantages of the present invention areidentified in the ensuing description, with reference to the drawingsidentified below.

BRIEF DESCRIPTION OF THE DRAWINGS

The purpose and advantages of the present invention will be apparent tothose of ordinary skill in the art from the following detaileddescription in conjunction with the appended drawings in which likereference characters are used to indicate like elements, and in which:

FIG. 1 is a diagram illustrating the elements of a typical wirelesslocal area network in accordance with at least one embodiment of thisinvention;

FIG. 2 illustrates the basic structure of a wireless LAN packetincluding a data frame containing wake-up data sequence in accordancewith at least one embodiment of this invention;

FIG. 3 illustrates the internal composition of the frame data of anwireless LAN packet containing a node specific wake-up data sequence inaccordance with at least one exemplary embodiment of this invention;

FIG. 4 is a block diagram illustrating the various internal componentsof a wireless device capable of entering a powered-down mode and furthercapable of being woken from a powered-down mode upon receipt of awake-up data sequence over a wireless LAN in accordance with at leastone exemplary embodiment of this invention;

FIG. 5 is a block diagram illustrating various components of a board orcard-based wireless LAN controller capable of generating a wake-upsignal in response to receive of a wireless LAN packet containing awake-up data sequence in accordance with at least one embodiment of thepresent invention;

FIG. 6 is a flow chart outlining the steps of a method for broadcastinga signal over a wireless LAN for waking a wireless devices from apowered down state in accordance with at least one embodiment of thepresent invention; and

FIG. 7 is a flow chart illustrating in greater detail the operation of awireless network controller during a powered down mode includingscanning a plurality of wireless data channels for information packetcontaining wake-up data sequence frame and exiting the powered down modeupon receipt of the wake-up data sequence frame in accordance with atleast one embodiment of this present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is intended to convey a thorough understandingof the present invention by providing a number of specific embodimentsand details involving the systems and methods which function to wake awireless device from a powered down mode via a wireless local areanetwork. It is understood, however, that the present invention is notlimited to these specific embodiments and details, which are exemplaryonly. It is further understood that one possessing ordinary skill in theart, in light of known systems and methods, would appreciate the use ofthe invention for its intended purposes and benefits in any number ofalternative embodiments, depending upon specific design and other needs.

For the purposes of this disclosure, the terms “MAGIC PACKET” and“wake-up data sequence” will be used interchangeably to refer to asequence of data contained in the frame data portion of a wireless LANinformation packet which uniquely identifies one or more nodes on thewireless LAN.

Also, for the purposes of this disclosure the terms “sleep mode”“reduced power mode” and “power saving mode” will be usedinterchangeably to refer to a computing device operating state enteredeither upon initiation by a user or after expiration of a period ofsufficient inactivity in which the amount of power supplied to thedevice is reduced as compared to amount supplied during normaloperation. This may include, but not is not limited to sleep modes whichare in compliance with U.S. Department of Energy EnvironmentalProtection Agency (EPA) Energy Star certification. These sleep modestypically include some combination of reduced operating power,withholding or reducing power to peripheral devices, reduced CPU clockspeed, spinning down of hard disc drives, etc.

For the purposes of this disclosure, the term “computing device” willrefer to lap top computers, notebook computers, desk top computers,tablet computers, palm computers, and other computing devices comprisingat least the fundamental components of a CPU, storage, a user interfaceand a communication bus.

For the purposes of this disclosure, the term “wireless network” willrefer to a local network such as a local area network within aparticular premises or discrete physical space, a distributed networksuch as a wide area wireless network, a collection of individual localarea network and combinations thereof.

FIG. 1 illustrates the basic elements of a wireless local area network(WLAN) 101 implemented at a customer premises 100. In various exemplaryembodiments, the customer premises 100 may be an office environmentcomprising a plurality of wireless computing devices. However, invarious other exemplary embodiments the customer premises 100 may be anyother type of business or residential environment where at least onewireless device is utilized over a WLAN.

In FIG. 1, a server computer 110 is connected to a wireless access point(AP) 120 via an Ethernet cable 115. Typically, the one or more wirelessaccess points 120 are mounted in elevated locations throughout thecustomer premises 101. The wireless access point 120 acts a transceiverto send data to and receive data from one or more wireless devices 130communicating with the WLAN 101. In various exemplary embodiments, thewireless access point 120 will include a transmitting antenna 121 fortransmitting the outbound LAN signal 125 and a receiving antenna 122 forreceiving the inbound LAN signal 126. Also shown in FIG. 1, are aplurality of wireless computing devices 130. For purposes of exampleonly, the wireless computing devices 130 shown in FIG. 1 are laptopcomputers. However, it should be appreciated that the wireless devicesmay be desktop computers, palm top computers, thin-client computers orvarious other computing devices. The present invention may be used withany and all types of computing devices communicating over a WLAN.

Referring again to FIG. 1, the wireless computing devices 130 willtypically each have a wireless network controller (not shown in FIG. 1)with an antenna (not shown) for receiving and transmitting signals toand from the wireless access point 120. As discussed above, in variousexemplary embodiments, the wireless network controller may be in theform of a separate card such as a PCMCIA card based network controller,a PCI card-based controller, a mini-PCI-based network controller orother card-based network controller. Alternatively, the wireless networkcontroller may be built into a different type of card or module or evenbuilt directly onto the system board of the computing device. Eachwireless computing device 130 activated on the WLAN 101 is considered anetwork node and is characterized by a hardware identification number.The wireless access point 120 is characterized to the wireless computingdevices 130 by a unique SSID.

Communication between wireless computing devices 130 and the wirelessaccess point 120 is based on data packets and is facilitated through theuse of the hardware identification number and the SSID. Thus, duringoperation, when data frames are sent to a particular wireless computingdevice 130 by the wireless access point 120, the wireless access point120 broadcasts the information over the entire WLAN 101. Contained ineach data frame of the signal 125 from the wireless access point is thedestination address or unique identification of the particular wirelesscomputing device 130 which is to receive the requested broadcast.Because the signal 125 is broadcast over the entire LAN 101, it isreceived by each wireless computing device 130 within the LAN 101. Acomparator in the wireless network controller of each wireless computingdevice 130 compares the destination address contained in the data frameswith its own destination address. If there is a match, the networkcontroller transfers the data frame to its wireless device 130.Otherwise, the data frame is ignored. Similarly, during upstream dataoperations, each wireless computing device 130 must specify the SSID ofthe wireless access point 120 in order for the upstream data signal tobe routed to the server 110. It should be noted that any wirelesscomputing device 130 (network), not only the server computer 110, may bethe source of the downstream data frame.

FIG. 2 illustrates the structure of an information packet 200 containinga wake-up data sequence for remotely waking at least one device nodethat is transmitted over the WLAN in accordance with at least oneembodiment of this invention. As discussed above in the context of FIG.1, this information packet 200 is generated by a source node remote fromthe wireless computing device receiving the information packet 200. Theinformation packet 200 is partitioned into 6 different fields inaccordance with basic LAN packet requirements. The first field containsthe 6-byte Destination Address 201 which indicates the hardware addressof the wireless computing device that is to receive the informationpacket 200. The second field contains the 6-byte Source Address 202which indicates the hardware address of the source node that generatedthe information packet 200. The third field is a 2-byte length field 203which contains the length of the frame data within the informationpacket 200. The fourth field is the Frame Data block 204 which containsthe actual information being transmitted. The Frame Data block 204 is avariable length field up to 1,404 bytes.

In a preferred embodiment, a 96-byte wake-up data sequence 205 iscontained in the Frame Data block 204. The wake-up data sequence 205comprises 16 consecutive repetitions of the Destination Address 201embedded anywhere in the Frame Data block 204. The wake-sequence is thesequence of numbers that actually causes a specific wireless device tobe woken from a sleep state. In various exemplary embodiments, the FrameData block 204 may contain a wake-up data sequence 205 for a singlewireless computing device. However, in various other embodiments, theFrame Data block 204 may contain a wake-up data sequence 205 for severalor all wireless computing devices within the influence of the WLANnetwork. Finally, the last field of the information packet 200 containsa 4-byte Cyclic Redundancy Check (CRC) error control code 206 forverifying the integrity of the data contained in the Frame Data block204. The format of packet-based communications signals is well known inthe art. Therefore, a complete discussion of packet-based communicationis intentionally omitted.

FIG. 3 illustrates an exemplary wake-up data sequence embedded in aninformation packet addressed to a wireless computing device having ahexadecimal based Ethernet hardware address of 1B:2B:3B:4B:5B:6B. InFIG. 3, for sake of simplicity, the Destination, Source and CRC fieldsare represented by their titles as opposed to their contents. Also, inFIG. 3, the portions of the Frame Data field surrounding the wake-updata sequence are denoted as Miscellaneous to highlight the wake-up datasequence. As shown in FIG. 3, the wake-up data sequence comprises 16consecutive iterations of the hexadecimal hardware address of thereceiving node. Also shown in FIG. 3, is a synchronization streamcomprised of 6 bytes of FF in hexadecimal directly preceding the 16consecutive iterations of the hardware address. The synchronizationstream allows the hardware which compares the Frame Data against theknown address to be implemented more simply.

The basic internal electronic system level components of an exemplarywireless computing device configured to accept wake-on wireless LAN inaccordance with at least one embodiment of this invention are shown inblock diagram form in FIG. 4. The wireless computing device shown inFIG. 4 is comprised of a microprocessor (CPU) 320, a memory 330, a harddisk 340, a network controller 360 and a power supply/management circuit350, all interconnected by a data/power bus 310. It should be noted thatthe network controller 360 may be implemented directly on the systemboard of the wireless computing device or may be located on an attachedbus board in electrical contact with the system board. Those havingordinary skill in the art will appreciate that the spirit and scope ofthis invention are not affected by the particular implementation of thenetwork controller 360. Furthermore, it should also be appreciated thatthe power supply/management circuit 350 may comprise a power storagedevice, a physical connection to line power, or a combination of both.Also shown in FIG. 4 is a separate data/power bus 370 interconnectingthe network controller 360 and the power supply/management circuit 350.In various exemplary embodiments, the separate data/power bus 370 willonly pass data signals between the power supply/management circuit 350and the network controller 360. In various other exemplary embodiments,the data/power bus 370 will supply power as well as passing data signalsbetween the power supply/management circuit 350 and the networkcontroller 360.

In a preferred embodiment, the network controller 350 is connected tothe wireless computing device by way of the PCI or mini PCI busarchitecture. The advantage of the PCI bus architecture in thisapplication is that the PCI bus supports both a 3V line and a 3.3 Vaux.Therefore, when the PCI bus in a D3cold state, that is when the PCIclock is disabled and the PCI bus power is disabled, 3.3 volts issupplied to the card on the 3.3 Vaux power rail. The 3.3 Vaux power railcan be used to supply power to the wireless wake-on-LAN enabled networkcard while the computing device is in the sleep mode. Therefore, littleor no modification of computing devices will be necessary to make themcompatible with wireless wake-on-LAN enabled network interface cards.

In a preferred embodiment, the wireless computing device of FIG. 4 islocated within the influence a wireless LAN. In various exemplaryembodiments, the device may already be configured to operate as a nodeon the wireless LAN. In various other exemplary embodiments, the devicemay not yet be configured to operate as a node on the wireless network.In order to maximize power savings in the sleep mode, when the wirelesscomputing device enters a sleep mode, the power supply/managementcircuit 360 preferably shuts down power to the system bus 310, CPU 320,memory 330 and hard disk 340. In order to speed up restart time, thecurrent contents of the memory 330 may be stored in the hard disk 340.The power management/supply circuit then sends a signal to the wirelessnetwork controller activating the wake-on wireless LAN mode over theseparate data/power bus 370 so that the wireless computing device may bewoken from the sleep mode upon receipt of the appropriate wake-up datasequence.

FIG. 5 illustrates in greater detail, components that comprise thenetwork controller 360 of FIG. 4 in accordance with at least oneexemplary embodiment of this invention. The network controller shown inFIG. 5, includes control logic 361, a transceiver 362 comprised of atiming control circuit 363, an N-channel scanner 364 and an antenna 365,a signal processor 366, a comparator 367 and an address memory 368. Whenthe computer is shut down, the power supply/management circuit 350 sendsa signal over the line 370 to the control logic circuit 361 to notifythe network controller 360 to enter the wireless wake-on frame detectionmode. The control logic circuit 361 notifies the timing control circuit363 of the transceiver 362 to begin the first timing sequence. The firsttiming sequence is an inactive wait sequence. After the first timingsequence has expired, the timing control circuit 362 activates theN-channel scanner 364 to sequentially scan each of a plurality of Nwireless channels for a predetermined period of time. The timing controlcircuit 363 activates a timer so that each of the plurality ofN-channels is scanned for a fixed period of time. During scanning, theN-channel scanner monitors a lead connected the antenna 365 over each ofthe N channels. Any incoming information packet received by the scanner364 is sent to the signal processor 366. The signal processor strips theheader, trailer and other miscellaneous data from the information packetto isolate the frame data containing the wake-up data sequence. Thisframe data is passed to the comparator 367. The comparator 367 comparesthe wake-up data sequence in the frame data of the information packetwith the network controller's 6-byte hardware identification addressstored in an address memory 368. When the wake-up data sequence of theframe data matches the address stored in the memory 367 the controllogic 368 sends a signal to the power supply/management circuit 350 towake-up the computing device over the bus 370.

FIG. 6 is a flow chart outlining the steps of a method for sending aninformation packet containing a wake-up data sequence over a wirelessLAN in accordance with at least one embodiment of this invention.Operation of the method begins in step S100 and proceeds to step S110where a broadcast timer is initialized. The broadcast timer determinesthe amount of time that the information packet containing the wake-updata sequence is broadcast for. Next, in step S120, an informationpacket carrying a frame containing at least one wake-up data sequence isbroadcast over the wireless LAN by a wireless access point. Operation ofthe method then proceeds to step s130. In step S130, a determination ismade whether a confirmation has been received that the frame data wassuccessfully received by the desired node and that the node has beenwoken and re-established connection to the LAN. If, in step S130, it isdetermined that no confirmation has been received, operation of themethod proceeds to step S140 where a determination is made whether apredetermined time for receiving a confirmation signal has expired. Aslong as the predetermined time has not expired, operation of the methodreturns to step S120 where the frame containing the wake-up datasequence is rebroadcast. Otherwise, if in step S140 it is determinedthat the predetermined time has expired, operation of the methodproceeds to step S160 where a notice that the server was unsuccessful inwaking the remote device is sent to the application which originated thewake-up signal. Operation of the method then terminates in step S170.

Returning to step S130, if in step S130 it is determined that aconfirmation has been received, operation proceeds to step S150. In stepS150 a notification signal is sent to the application which originatedthe wake-up signal notifying the application that the particular nodehas been successfully woken. Operation of the method then terminates instep S170.

FIG. 7 is flow chart outlining the steps of a method of scanning for andreceiving an information packet carrying frame data having a wake-updata sequence in accordance with at least one embodiment of thisinvention Operation of the method begins in step S200 and proceeds tostep S205 where the wireless computing device enters the sleep mode.Next, in step S210, the network controller of the wireless computingdevice enters the wake-up data sequence detection mode in response to asignal from the power supply/management circuit that the device hasentered the sleep mode. Then, operation of the method proceeds to stepS215 where the inactivity timer T1 is initiated. The inactivity timer T1counts down a predetermined inactivity time to wait prior to scanningfor wake-up signals and between successive scans for wake-up signals.Next, in step S220, a determination is repeatedly made as to whether theinactivity timer T1 has expired. Until it is determined that theinactivity timer T1 has expired, the determination of step S220 isrepeated. Otherwise, processing proceeds to step S225.

In step S225 the scanning receiver is activated to scan for aninformation packet containing a wake-up data sequence on the first datachannel. Next, in step S230, a channel scanning timer is activated whichsets the time that the receiver monitors the current channel. Then, instep S235, scanning of the channel begins. After a period of delay lessthan the timer T, processing proceeds to step S240. In step S240, adetermination is made whether an information packet has been received onthe current channel. If, in step S240, it is determined that aninformation packet has been received on the current channel, operationof the method proceeds to step S250. Otherwise, operation proceeds tostep S245. In step S245, a determination is made whether channelscanning timer has expired. If, in step S245, it is determined that thescanning timer has expired, operation of the method proceeds to stepS255. Otherwise, operation of the method jumps back to step S235 wherethe channel continues to be scanned.

In step S255, a determination is made whether all N channels have beenscanned. If, in step S255, it is determined that all N channels havebeen scanned, operation advances to step S265 where the scanningreceiver is deactivated. Then operation returns to step S215 where theinactivity timer is again started. Otherwise, if at S255, it isdetermined that all channels have not be scanned, operation advances tostep S260 where the current channel is incremented to the next channeland then returns to step S230 where the timer is restarted.

Returning to step S250, if a positive determination is made in stepS240, a determination is made whether the wake-up data sequence in thedata frame received on the current channel contains a properly formattedwake-up data sequence which specifically identifies the LAN controllerof the device. If, in step S250, it is determined that the informationpacket does contain a properly formatted wake-up data sequence,operation proceeds to step S270. Otherwise, operation goes to step S245.In step S270, the wake-up data sequence detecting mode is disabled.Then, operation of the method proceeds to step S275 where a signal issent to the power supply/management circuit to wake-up the device. Next,in step S280, a confirmation signal is sent by the LAN controller to thewireless access point to notify the application that originated thewake-up that node has been successfully woken. Finally, operation of themethod terminates in step S285.

While the foregoing description includes many details and specificities,it is to be understood that these have been included for purposes ofexplanation only, and are not to be interpreted as limitations. Manymodifications and equivalent substitutions to the embodiments describedabove can be made without departing from the spirit and scope of theinvention.

The invention claimed is:
 1. A method comprising: monitoring a pluralityof wireless channels for a wake-up packet addressed to a wireless deviceduring a monitor timeframe, wherein the wake-up packet is configured tocause the wireless device to initiate a transition from operating in afirst power mode to operating in a second power mode; transitioning fromoperating the wireless device in the first power mode to operating thewireless device in the second power mode when a wake-up packet addressedto the wireless device has been received before the monitor timeframehas elapsed; and ceasing to monitor the plurality of wireless channelswhen a wake-up packet addressed to the wireless device has not beenreceived after the monitor timeframe has elapsed.
 2. The method of claim1, further comprising: resuming monitoring of the plurality of wirelesschannels for a wake-up packet addressed to the wireless device duringthe monitor timeframe after an inactivity timeframe has elapsed.
 3. Themethod of claim 1, wherein monitoring the plurality of wireless channelsfor a wake-up packet addressed to a wireless device during the monitortimeframe comprises sequentially monitoring individual wireless channelsof the plurality of wireless channels for a corresponding subdivision ofthe monitor timeframe until either the monitor timeframe has elapsed,until a wake-up packet has been received by the wireless device, oruntil each wireless channel of the plurality of wireless channels hasbeen monitored.
 4. The method of claim 1, further comprising: initiatingthe transmission of a confirmation packet when the wireless device hascompleted the transition from operating in the first power mode tooperating in the second power mode.
 5. The method of claim 1, whereinthe wireless device has a wireless hardware address, and wherein thewake-up packet comprises multiple consecutive iterations of the hardwareaddress of the wireless device.
 6. The method of claim 1, wherein thewake-up packet is a broadcast packet addressed to a plurality ofwireless devices on a wireless local area network, and wherein thewake-up packet is configured to cause each wireless device of theplurality of wireless devices on the wireless local area networkcurrently operating in the first power mode to initiate the transitionfrom the first power mode to the second power mode.
 7. The method ofclaim 1, wherein the power required for operating the wireless device inthe first power mode is less than the power required for operating thewireless device in the second power mode.
 8. An apparatus comprising: acontroller configured to monitor a plurality of wireless channels for awake-up packet addressed to a wireless device during a monitortimeframe, wherein the wake-up packet is configured to cause thewireless device to initiate a transition from operating in a first powermode to operating in a second power mode, wherein the controller isconfigured to initiate the transition from operating the wireless devicein the first power mode to operating the wireless device in the secondpower mode when a wake-up packet addressed to the wireless device hasbeen received before the monitor timeframe has elapsed, and wherein thecontroller is configured to cease to monitor the plurality of wirelesschannels when a wake-up packet addressed to the wireless device has notbeen received after the monitor timeframe has elapsed.
 9. The apparatusof claim 8, wherein the controller is further configured to resumemonitoring the plurality of wireless channels for a wake-up packetaddressed to the wireless device during the monitor timeframe after aninactivity timeframe has elapsed.
 10. The apparatus of claim 8, whereinthe controller is further configured to sequentially monitor individualwireless channels of the plurality of wireless channels for acorresponding subdivision of the monitor timeframe until either themonitor timeframe has elapsed, until a wake-up packet has been received,or until each wireless channel of the plurality of wireless channels hasbeen monitored.
 11. The apparatus of claim 8, wherein the wirelessdevice is configured to initiate the transmission of a confirmationpacket when the wireless device has transitioned from operating in thefirst power mode to operating in the second power mode.
 12. Theapparatus of claim 8, wherein the wireless device has a wirelesshardware address, and wherein the wake-up packet comprises multipleconsecutive iterations of the hardware address of the wireless device.13. The apparatus of claim 8, wherein the wake-up packet is a broadcastpacket addressed to plurality of wireless devices on a wireless localarea network, and wherein the wake-up packet is configured to cause eachwireless device of the plurality of wireless devices on the wirelesslocal area network currently operating in the first power mode toinitiate the transition from the first power mode to the second powermode.
 14. The apparatus of claim 8, wherein the power required foroperating the wireless device in the first power mode is less than thepower required for operating the wireless device in the second powermode.
 15. An apparatus comprising: means for monitoring a plurality ofwireless channels for a wake-up packet addressed to a wireless deviceduring a monitor timeframe, wherein the wake-up packet is configured tocause the wireless device to initiate a transition from operating in afirst power mode to operating in a second power mode; means fortransitioning from operating the wireless device in the first power modeto operating the wireless device in the second power mode when a wake-uppacket addressed to the wireless device has been received before themonitor timeframe has elapsed; and means for ceasing to monitor theplurality of wireless channels when a wake-up packet addressed to thewireless device has not been received after the monitor timeframe haselapsed.
 16. The apparatus of claim 15, further comprising: means forresuming monitoring of the plurality of wireless channels for a wake-uppacket addressed to the wireless device during the monitor timeframeafter an inactivity timeframe has elapsed.
 17. The apparatus of claim15, wherein the means for monitoring the plurality of wireless channelsfor a wake-up packet addressed to a wireless device during the monitortimeframe comprises means for sequentially monitoring individualwireless channels of the plurality of wireless channels for acorresponding subdivision of the monitor timeframe until either themonitor timeframe has elapsed, until a wake-up packet has been receivedby the wireless device, or until each wireless channel of the pluralityof wireless channels has been monitored.
 18. The apparatus of claim 15,further comprising: means for initiating the transmission of aconfirmation packet when the wireless device has completed thetransition from operating in the first power mode to operating in thesecond power mode.
 19. The apparatus of claim 15, wherein the wirelessdevice has a wireless hardware address, and wherein the wake-up packetcomprises multiple consecutive iterations of the hardware address of thewireless device.
 20. The apparatus of claim 15, wherein the wake-uppacket is a broadcast packet addressed to plurality of wireless deviceson a wireless local area network, and wherein the wake-up packet isconfigured to cause each wireless device of the plurality of wirelessdevices on the wireless local area network currently operating in thefirst power mode to initiate the transition from the first power mode tothe second power mode.
 21. The apparatus of claim 15, wherein the powerrequired for operating the wireless device in the first power mode isless than the power required for operating the wireless device in thesecond power mode.
 22. A non-transitory computer-readable medium havinginstructions stored thereon that, if executed by a computing device,cause the computing device to perform operations comprising: monitoringa plurality of wireless channels for a wake-up packet addressed to awireless device during a monitor timeframe, wherein the wake-up packetis configured to cause the wireless device to initiate a transition fromoperating in a first power mode to operating in a second power mode;transitioning from operating the wireless device in the first power modeto operating the wireless device in the second power mode when a wake-uppacket addressed to the wireless device has been received before themonitor timeframe has elapsed; and ceasing to monitor the plurality ofwireless channels when a wake-up packet addressed to the wireless devicehas not been received after the monitor timeframe has elapsed.
 23. Thenon-transitory computer-readable medium of claim 22, wherein thecomputing device is further configured to perform operations comprising:resuming monitoring of the plurality of wireless channels for a wake-uppacket addressed to the wireless device during the monitor timeframeafter an inactivity timeframe has elapsed.
 24. The non-transitorycomputer-readable medium of claim 22, wherein monitoring the pluralityof wireless channels for a wake-up packet addressed to a wireless deviceduring the monitor timeframe comprises sequentially monitoringindividual wireless channels of the plurality of wireless channels for acorresponding subdivision of the monitor timeframe until either themonitor timeframe has elapsed, until a wake-up packet has been receivedby the wireless device, or until each wireless channel of the pluralityof wireless channels has been monitored.
 25. The non-transitorycomputer-readable medium of claim 22, wherein the computing device isfurther configured to perform operations comprising: initiating thetransmission of a confirmation packet when the wireless device hascompleted the transition from operating in the first power mode tooperating in the second power mode.
 26. The non-transitorycomputer-readable medium of claim 22, wherein the wireless device has awireless hardware address, and wherein the wake-up packet comprisesmultiple consecutive iterations of the hardware address of the wirelessdevice.
 27. The non-transitory computer-readable medium of claim 22,wherein the wakeup packet is a broadcast packet addressed to a pluralityof wireless devices on a wireless local area network, and wherein thewake-up packet is configured to cause each wireless device of theplurality of wireless devices on the wireless local area networkcurrently operating in the first power mode to initiate the transitionfrom the first power mode to the second power mode.
 28. Thenon-transitory computer-readable medium of claim 22, wherein the powerrequired for operating the wireless device in the first power mode isless than the power required for operating the wireless device in thesecond power mode.